How to ensure this cake won't fall!

AHey guys,
I am making this cake for a friend and she would like the bottom tier to be 12" and the top 10inch.
What kind of supports should I use? I know a lot of you like the SPS but it's just too hard for me to get as I love in a small town in Australia with no cake decorating supply shop.
Also how many inches high would this cake be? And many extra serves do you think a 12inch would be that is that high.

Any help would be really appreciated!! [IMG]http://cakecentral.com/content/type/61/id/3143869/width/200/height/400[/IMG]

A 12" and 10" would be enormous...That photo look like an 8" and double barrel 9" to me, it the tiers are 4" tall.

I just use regular wooden dowels. I'd do two 9" tiers stacked on top of each other (same thing if it's 12" tiers that you do use) and dowel them normally, then stack the top tier after dowelling the bottom double barrel. As long as there are enough dowels and they're supporting the tiers correctly there's no reason that you'd need a special support system.

Boy, as costume mentioned a 12 & 10 cake is going to be super big! :) It would serve - if I remember right - somewhere around 150. I agree w/her that the bottom tier is 6 or 8" tall w/the top tier 4". That means baking 4 layers of the larger size and 2 for the top tier. And it's not going to look the same in that larger size.

Remember Australian serving sizes are HALF as big as US ones - 1inch x 1inch x height of 'standard' cake (4inches) - when you do an extended tier (such as in your example) you in fact have a 3 tier cake where the 2 bottom tiers are stacked on top of each other (there are dowels and board hidden internally in that base tier)

A 9inch base x 2 + 6inch will yield 138 serves

A central dowel (12.5mm) glued into base boards - all HD MDFwill make it stable if you need to transport (I have experience on Australian country roads!! )
If you choose this system remember to predrill all your STD boards as well

This is quite a challenging cake for somebody that perhaps does not have a lot of experience. It is also NOT a cheap cake.

AThis is just for a close friend and I won't be charging for it!! It will cost me around $100 to make so it's a 21st present.
I have made a 12inch and 10inch before which I think was around 80 serves and I had no problems doing it. I'm going to tell her to just pick a normal 2 teir cake.

One thing I learned about making ggod cakes.....always use very cold water if the recipe calls for water. Always use large eggs, not medium or small, and always let them get room temperature. Never over beat as you will beat too much air into the batter, and a trick that my Mother taught me that I use without tfail, add a large teaspoon of Hellmanns Mayonnaise to every mix!!!

Here's a visual of the support system that Pam was referring to-great for traveling!

Yes, a 12" is huge and heavy! So whatever you decide to do make sure your base (bottom board) is sturdy enough to hold the weight of the entire cake (both tiers).

As the others mentioned, a 10&12" would look strange to me (again with the double barrel/extended tier it will be heavy)!!! If it were me I would offer cupcakes for extra servings or simply add a tier, I think you (and your customer) will be much happier with the end result.

AHow many people does the cake need to serve? I just did a cake for 100 and I did an 10" double barrel, 8", and 6" double barrel.

I doweled the tiers at home and stacked on site. I live in the foothills around Adelaide and was to nervous to stack it and transport with all of the hills.

For the double barrels I put 5 dowels into the bottom half, a cardboard cake board after layer four, and 5 mire dowels after covering with fondant. I used 5 dowels in the 8." I also only doweled and put a cardboard cake board in the bottom of the 6" (I only used 4 dowels.

This was my first big cake ... [IMG ALT=""]http://cakecentral.com/content/type/61/id/3144857/width/350/height/700[/IMG]

Ok thanks guys!! What would you suggest for a cake to feed 100 people? She only wants 2 tiers.

Sorry if I'm too late to comment here but just in case:

I'm more inclined to make a cake that's aesthetically pleasing than worry too much about how many people it will serve. If it's too small, then you can make a "kitchen cake" (same flavour cake and icing but no decoration) to be cut up and served with the decorated cake. If it's too large, then you can make some of the tiers dummy cakes.